//=============================================================================
//
//  Copyright (c) Kitware, Inc.
//  All rights reserved.
//  See LICENSE.txt for details.
//
//  This software is distributed WITHOUT ANY WARRANTY; without even
//  the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
//  PURPOSE.  See the above copyright notice for more information.
//
//=============================================================================
#include "smtk/mesh/moab/IncrementalAllocator.h"
#include "smtk/mesh/moab/CellTypeToType.h"

#include "smtk/mesh/core/CellTypes.h"

#include "smtk/common/CompilerInformation.h"

SMTK_THIRDPARTY_PRE_INCLUDE
#include "moab/Interface.hpp"
#include "moab/ReadUtilIface.hpp"
SMTK_THIRDPARTY_POST_INCLUDE

#include <cassert>

namespace
{
// must be a power of two
const std::size_t StartingAllocation = 64; // (1<<6)
} // namespace

namespace smtk
{
namespace mesh
{
namespace moab
{

IncrementalAllocator::IncrementalAllocator(::moab::Interface* interface)
  : BufferedCellAllocator(interface)
  , m_index(0)
{
}

void IncrementalAllocator::initialize()
{
  if (m_nCoordinates == 0)
  {
    this->IncrementalAllocator::allocateCoordinates(StartingAllocation);
  }
}

bool IncrementalAllocator::allocateCoordinates(std::size_t nCoordinates)
{
  m_validState = this->BufferedCellAllocator::allocatePoints(
    nCoordinates, m_firstCoordinate, m_coordinateMemory);

  if (m_validState)
  {
    m_nCoordinates += nCoordinates;
  }

  m_coordinateMemories.push_back(m_coordinateMemory);

  return m_validState;
}

std::size_t IncrementalAllocator::addCoordinate(double* xyz)
{
  if (!m_validState)
  {
    return false;
  }

  if (m_nCoordinates <= m_index)
  {
    this->IncrementalAllocator::allocateCoordinates(m_nCoordinates);
    if (!m_validState)
    {
      return m_index;
    }
  }

  m_validState = this->IncrementalAllocator::setCoordinate(m_index, xyz);

  return m_index++;
}

bool IncrementalAllocator::setCoordinate(std::size_t coord, double* xyz)
{
  if (!m_validState)
  {
    return false;
  }

  if (coord >= m_nCoordinates)
  {
    return false;
  }

  // Coordinates are allocated using a memory doubling scheme, and we need to
  // figure out
  // (a) <exp>, the chunk of allocated memory in which <coord> resides, and
  // (b) <offset>, or starting index for chunck <exp>.
  // We do this by performing successive integer divisions by two (c >>= 1)
  // while keeping track of the number of divisions we have performed (++exp)
  // and by performing successive integer doublings of our offset by two
  // (offset <<= 1).

  std::size_t exp = 0;
  std::size_t offset = StartingAllocation >> 1;

  for (std::size_t c = coord; c >= StartingAllocation; c >>= 1)
  {
    ++exp;
    offset <<= 1;
  }

  if (exp > 0)
  {
    coord -= offset;
  }

  m_coordinateMemories[exp][0][coord] = xyz[0];
  m_coordinateMemories[exp][1][coord] = xyz[1];
  m_coordinateMemories[exp][2][coord] = xyz[2];

  return m_validState;
}
} // namespace moab
} // namespace mesh
} // namespace smtk
